In U.S. Pat. No. 5,148,310, “Rotating flat screen fully addressable volume display system,” an angular multiplanar volumetric display system was described that solved a number of the problems related to the generation of three-dimensional (3-D) images. That invention, like others in its class, was based in part on the projection of scanned images onto a moving, and in this case, rotating, display screen. The benefits of multiplanar techniques over other methods for achieving 3-D imaging, include a wide field of view and observation without requiring the use of special viewing glasses.
Despite the benefits mentioned above, many problems still exist in the generation of practical 3-D displays. The first problem is that of making the entire system solid-state, i.e., having no moving parts.
Another problem is that the displayed images should exist in free space, i.e., wherein the display region is generally not enclosed or occupied by a substrate material.
Yet another problem is that an observer should be able to control the display system with the use of a physical pointer. Ideally, observers could control the display by merely reaching into the display region and “touching” desired 3-D image with their hand or finger.
A further problem is that the display should be widely scalable in parameters such as size, resolution, gray-scale and color. Fifth, the display should be simple to produce, compact and have relatively low cost.
Another problem is that any portion of the display region should be randomly addressable without dependence on a faster scan rate.
Still a further problem is that the refresh rate of the display should be scalable, beyond the 20–60 Hz requirement of human persistence of vision, to the range of kHz or faster for increased resolution and additional applications, i.e., such as machine vision, data storage, optical computing and optical networking, etc.
Above, several well-known problems that relate to the engineering of 3-D displays have been described; in fact, these problems are a subset of the broad challenges sweeping throughout many applications of optics in general.